Field of the Invention
The present invention relates to a vibration module including a piezoelectric device, and more particularly, to a vibration module including a piezoelectric device, which reinforces durability of the vibration module mounted in speakers, mobile devices, and others and enhances vibration performance.
Background Art
A specific crystal convertible between mechanical energy and electric energy is called a piezoelectric crystal, and a device manufactured by applying the piezoelectric crystal is called a piezoelectric device. When a potential is applied to the piezoelectric crystal, there is a slight change in the form of the crystal, and when a physical pressure is applied to the piezoelectric crystal, there is a potential difference between both sides of the crystal. The piezoelectric crystal is used in some of microphones for converting the mechanical energy of sound waves into an electric signal or crystal oscillators which help in controlling oscillation frequencies using mechanical properties of crystal. A piezo-resonant package is a device that single parts are manufactured in a package form using the piezoelectric device.
Moreover, the piezoelectric device is used in speakers for generating sounds by vibration, actuators, and others. Ceramic-based piezoelectric device is small in size and is operatable at low voltage and low power, and hence, is widely adopted as a device for generating vibration of mobile devices.
FIG. 1 illustrates a conventional vibration module based on a piezoelectric device. In the conventional vibration module, the piezoelectric device and a vibration plate are bonded together with an adhesive, and the vibration plate is connected with the outside (polymer). When the mechanical energy generated by the piezoelectric device is transferred to the vibration plate, the vibration plate vibrates the polymer based on the mechanical energy. So, the mobile devices or others can be vibrated.
However, the conventional vibration module is weak to external shock due to its ceramic properties. Particularly, in case of the mobile device, the conventional vibration module has a problem in that the ceramic-based piezoelectric device is damaged due to a shock applied when a user drops the mobile device to the floor due to the user's carelessness.
Furthermore, when the piezoelectric device is operated, the vibration plate and the piezoelectric device are different in movement from each other due to a difference in material, and thereby, the vibration plate and the piezoelectric device bonded by the adhesive may be separated from each other. Additionally, an external device connected by a contact terminal may be also separated from the piezoelectric device according to vibration of the piezoelectric device.